Typically, lithium-ion cells contain a liquid electrolyte comprising flammable organic solvents. If the cell is exposed to physical or electrical abuse, such as shorting, external heating, overcharge or overdischarge the cell can enter thermal runaway conditions, whereby the flammable liquid electrolyte is vaporised and, in extreme circumstances, ejected from the cell. The release of flammable materials, combined with an elevated cell temperature presents an inherent fire hazard. In order to mitigate the risk associated with liquid electrolytes, it is known to use gel electrolytes.
US2003/0194607A describes a method of making a lithium-ion cell having a gel electrolyte by assembling the components of the cell and then subjecting the assembled cell to a polymer gel formation process by heating in order to form a polymer-gel electrolyte.
The process of forming the polymer-gel electrolyte using this method is both time consuming and costly.